1. Field of the Invention
The present invention is directed to a dual use or combination fluid filtration tool to separate both solid particles and gas from fluid. In particular, the present invention is directed to a dual use fluid filtration tool to separate both solid particles and gas wherein the tool is used with a downhole submersible pump having a motor which rotates a shaft that passes through the tool.
2. Prior Art
Various types of pumps and similar devices are used to move fluids from beneath the surface of the earth to the surface. Well known applications include oil and gas wells and water wells. A typical downhole arrangement would include a string composed of a series of tubes or tubing suspended from the surface. One type of well-known pump is a downhole electrical submersible pump. The electrical submersible pump either includes or is connected to a downhole motor which is sealed so that the whole assembly is submerged in the fluid to be pumped. The motor is connected to a power source at the surface and operates beneath the level of fluid downhole in order to pump the fluid to the surface. A component is connected to the motor which prevents well fluid from entering the motor and equalizes internal motor pressure with the well annulus pressure. The component is commonly known as a protector, seal or equalizer.
Single stage submersible pumps are utilized in drainage and industrial pumping applications. Multiple stage submersible pumps are often used in oil wells and include a staged series of centrifugal pumps to move the fluid to the surface.
A number of factors may be detrimental to the production of an electrical submersible pump. One detrimental factor is the presence of foreign solid particles, such as sand, sediment, and scale. The amount and size of foreign solid particles in the fluid may vary widely depending on the well and the conditions encountered. In enhanced recovery operations, for example, fluids may be pumped down the well to stimulate production causing additional movement of sands and solids. The solid particles act as abrasives and, over time, are detrimental to the operation of the pump. Pumps and motors may rotate at from 2575 to 4600 rpm and have tight clearances and, accordingly, are not tolerant of solids.
A further detrimental factor is encountered in wells which contain an excess amount of gas or gas bubbles. If too much gas or gas bubbles enters the intake of the pump, it will cause the pump to decrease in efficiency. It is known that the electrical submersible pumps have dramatically lower efficiencies with significant fractions of gas. At some point, the pump may become “gas locked” and damage to the pump and/or motor may result.
Various proposals in the past have been made to filter solid particles from fluid pumps. Various proposals have also been made in the past to prevent or alleviate gas lock conditions from fluid pumps. Some of the various prior art proposals in the past include the following:
Miller (U.S. Pat. No. 4,977,958) discloses a pump filter which connects to a lower end of a pump with a mandrel 50, a surrounding filter sock and surrounding tubular casing with perforations to filter sand and other solids.
Cobb (U.S. Pat. No. 6,382,317) discloses a gas-solid separator 34 in a string with a pump 18 wherein a separator 34 has an outer tubular member 44. A gas spiral 66 directs gas upwardly in an annulus for discharge. A solid spiral 70 separates solids from the liquid.
Cobb (U.S. Reissue Pat. No. RE 35,454) discloses a downhole solid particle separator including an inner tube within an outer tube which is located below a pump. A spiral guide defines an orifice for the fluid. In the FIG. 6 embodiment, a gas trap tube 33b traps gas in the fluid.
Burnside (U.S. Pat. No. 3,730,268) discloses a well filter device 10 having an outer shell 11 with slots 12 and an inner cylindrical screen 13 which is coaxial with a shell used to remove foreign materials standing in a well casing.
Price (U.S. Pat. Nos. 4,241,787 and 4,296,810) discloses a separator assembly 32 for separating oil and water having an outer shell connected to a pump intake, a lower end having perforations and a collector tube with a laminated filter element.
Koehler et al. (U.S. Pat. No. 5,664,628) discloses a downhole filter which includes a perforated inner support member 11 with one or more layers 13 of porous filter medium wrapped around inner support member 11.
Malbrel et al. (U.S. Pat. No. 5,881,812) discloses a downhole filter having an inner support member 10, a filter body surrounding the inner support member and an external cage 24.
Bode et al. (U.S. Pat. No. 6,352,111) discloses a downhole filter 18 including a perforated inner member 31 and a filter membrane 33 which is wrapped around an inner member.
Ford et al. (U.S. Pat. No. 6,736,880) discloses a gas separator used in conjunction with a pump and motor including an interior cavity with a rotary separator and a vertical gas outlet passage 46.
Hopper (U.S. Pat. No. 6,860,921) discloses a downhole centrifugal liquid/gas separator located above a pump 26.
Notwithstanding the foregoing, there remains a need to provide a combination or a dual use downhole fluid filtration tool that will be capable of separating solids and solid particles from fluid and also a need to prevent an undue amount of gas from entering the fluid prior to entering the pump.
There also remains a need to provide a combination or dual use fluid filtration tool which will be connected to and be suspended from a submersible pump and operate as an intake to said pump.
While it is possible to add filtering components on to existing equipment, it is not desirable to increase the outside diameter of the equipment.
There also remains a need to provide a combination or dual use downhole fluid filtration tool that has an outside diameter no greater than the outside diameter of the existing downhole components.